Battery drain

Hi everybody,
I would really need your help!
I was driving last weekend out for holiday. Suddenly a battery sign turned on and after a short while everything was turned off by the ECU.
I could get a new battery and everything looked fine when batt light on dash came back but only under low rpm. While I am incrised rpm batt light turned off. After a while this did not worked at all and my car started to shot off the system due to low voltage with batt light on permanently again.
Finally arrived on a trailer to my holiday accomodation and now i am trying to figure out what could be the problem.
Yesterday both batt recharged in order to move my car to workshop which is in 50 km away but could run 15 km with each only with a same sympthons. With charged batt dash light goes off and a short while it gets back and finally shots off everything.
If you faced with this please share your experience with me...
I don't know at this moment how will I get home....Greece to Hungary....

Ha tudnám hogyan lesz privát...

That was my thought as well...but dash light should not be on all time?

Update...today alternator/generator removed by myself...workshops are to busy.
Was not easy on allroad but it is done.
The new part is coming from home by an unknown heartfull body.
I had to release aircomp with its holder to get enough space for gen way out.

Finally...generator replaced...
Was fun without spec tool for tension, specially serpentine belt back but I could complete it with a strong rope. No need to remove radiators at all....
Total time was about 10 hrs from beginning till the finish but it was under the Greek sun...appr 35 degrees...forgive me
But it works!!!!

But!!! This was not the end...
On the way home the aircon compressor stucked which means that serpentine belt came out in two peaces in the middle of nowhere...
I do not want to take your time... it is just to learn something...
We figured out that during last service in Austria they put on a 3 cm shorter belt. I had a 2460 mm on my car which is not for an automatic transmission type. For this type a 2490 mm is needed. So this might be behind all fault i have had during my "holiday" trip. This short belt pulled everything horizontaly and verticaly as well.
Cheers for everyone!